Final answer:
Government agencies traditionally led voter registration, but now advocacy groups are more actively involved.
Step-by-step explanation:
Traditionally, government agencies were the leaders in voter registration activity. More recently, advocacy groups have taken a more active role. This shift can be seen in the activities of organizations like the Association of Community Organizations for Reform Now (ACORN), and initiatives such as Rock the Vote and When We All Vote that aim to engage specific demographics like the youth. These groups tackle the challenge of registering new voters, particularly in states that do not have automatic voter registration, unlike some countries that automatically register citizens to vote.
Given the context provided, the correct answer to the fill-in-the-blank question is: Traditionally, government agencies were the leaders in voter registration activity. More recently, advocacy groups have taken a more active role.